Whole Watershed Permitting: Neuse River Basin Case Study

摘要

The Neuse River Estuary in North Carolina is impaired by eutrophication attributed to watershed nutrient loads. On December 11,1997, the North Carolina Environmental Management Commission approved the Neuse River Nutrient Sensitive Waters Management Strategy Rules (hereafter called the Rules). The Rules were subsequently approved and put into effect by the General Assembly on August 1,1998. The Rules include mandatory measures for point and nonpoint sources of nutrients to achieve the goal of reducing nitrogen delivered to the estuary by 30 percent within 5 years. (Point source requirements for the control of phosphorus are also included.) Load reductions were mandated for source categories (point sources, urban stormwater, and agriculture) and requirements made of individual sources within categories. The Rules allow coalitions to form and to develop collective approaches, which are more cost effective than individual permit or best management practice (BMP) requirements. Using point sources as an example, the Rule requires that point sources reduce their annual nitrogen load from the current 4.1 million pounds per year to 2.8 million pounds. The 2.8 million pounds are allocated among three different types of basin dischargers, which vary by volume of discharge and location in the basin. The nitrogen allocated to individual dischargers is based on a ratio of their permitted flow to the sum of total permitted flow. Dischargers have the option of joining a dischargers' coalition to implement more cost-effective controls, to purchase nitrogen offset allowances, or to purchase a portion of the nonpoint source allocation. Importantly, the dischargers' permit requirements are set in light of total watershed loading from all sources, the overall reduction goal, and reductions required of other sources. Essentially, this is whole watershed permitting. This paper will focus on why the Nutrient Sensitive Water Rules were developed, Rule requirements and allowances, concerns raised during Rule development, and experience to date in implementing the Rules. It concludes with some key lessons learned.